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    <div class="example" id="signals">
      <h2><a href="./">Go by Example 中文版</a>: 信号</h2>
      
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            <p>有时候，我们希望 Go 可以智能的处理 <a href="http://en.wikipedia.org/wiki/Unix_signal">Unix 信号</a>。
例如，我们希望当服务器接收到一个 <code>SIGTERM</code> 信号时，能够优雅退出，
或者一个命令行工具在接收到一个 <code>SIGINT</code> 信号时停止处理输入信息。
我们这里讲的就是在 Go 中如何使用通道来处理信号。</p>

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            <a href="http://play.golang.org/p/HBLH7B0SxOR"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
          <div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
</pre></div>

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          <div class="highlight"><pre><span class="kn">import</span> <span class="p">(</span>
    <span class="s">&quot;fmt&quot;</span>
    <span class="s">&quot;os&quot;</span>
    <span class="s">&quot;os/signal&quot;</span>
    <span class="s">&quot;syscall&quot;</span>
<span class="p">)</span>
</pre></div>

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          <div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
</pre></div>

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            <p>Go 通过向一个通道发送 <code>os.Signal</code> 值来发送信号通知。
我们将创建一个通道来接收这些通知（同时再创建一个在程序结束时发送通知的通道）。</p>

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          <div class="highlight"><pre>    <span class="nx">sigs</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="nx">os</span><span class="p">.</span><span class="nx">Signal</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span>
    <span class="nx">done</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">bool</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span>
</pre></div>

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            <p><code>signal.Notify</code> 注册给定的通道，用于接收特定信号。</p>

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          <div class="highlight"><pre>    <span class="nx">signal</span><span class="p">.</span><span class="nx">Notify</span><span class="p">(</span><span class="nx">sigs</span><span class="p">,</span> <span class="nx">syscall</span><span class="p">.</span><span class="nx">SIGINT</span><span class="p">,</span> <span class="nx">syscall</span><span class="p">.</span><span class="nx">SIGTERM</span><span class="p">)</span>
</pre></div>

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            <p>这个协程执行一个阻塞的信号接收操作。
当它接收到一个值时，它将打印这个值，然后通知程序可以退出。</p>

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          <div class="highlight"><pre>    <span class="k">go</span> <span class="kd">func</span><span class="p">()</span> <span class="p">{</span>
        <span class="nx">sig</span> <span class="o">:=</span> <span class="o">&lt;-</span><span class="nx">sigs</span>
        <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">()</span>
        <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">sig</span><span class="p">)</span>
        <span class="nx">done</span> <span class="o">&lt;-</span> <span class="kc">true</span>
    <span class="p">}()</span>
</pre></div>

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            <p>程序将在这里进行等待，直到它得到了期望的信号
（也就是上面的协程发送的 <code>done</code> 值），然后退出。</p>

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          <div class="highlight"><pre>    <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">&quot;awaiting signal&quot;</span><span class="p">)</span>
    <span class="o">&lt;-</span><span class="nx">done</span>
    <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">&quot;exiting&quot;</span><span class="p">)</span>
<span class="p">}</span>
</pre></div>

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            <p>当我们运行这个程序时，它将一直等待一个信号。
通过 <code>ctrl-C</code>（终端显示为 <code>^C</code>），我们可以发送一个 <code>SIGINT</code> 信号，
这会使程序打印 <code>interrupt</code> 然后退出。</p>

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          <div class="highlight"><pre><span class="gp">$</span> go run signals.go
<span class="go">awaiting signal</span>
<span class="go">^C</span>
<span class="go">interrupt</span>
<span class="go">exiting</span>
</pre></div>

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